The exemplary embodiments described herein relate to engineering bead slurries for use in producing lightweight cement slurries for use in conjunction with subterranean cementing operations.
Hydraulic cement compositions are commonly used in oil, gas and water well completion and remedial operations. For example, hydraulic cement compositions are used in primary cementing operations whereby strings of pipe such as casing and liners are cemented in well bores. In performing primary cementing, a hydraulic cement composition is pumped into the annular space between the walls of a well bore and the exterior of a string of pipe disposed therein. The cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened substantially impermeable cement therein. The cement sheath physically supports and positions the pipe in the well bore and bonds the pipe to the walls of the well bore whereby the undesirable migration of fluids between zones or formations penetrated by the well bore is prevented.
In some locations, the subterranean zones or formations into or through which wellbores are drilled have high permeabilities and low compressive and tensile strengths. As a result, the resistance of the zones or formations to shear are low and they have low fracture gradients. When a hydraulic cement composition is introduced into a well bore penetrating such a subterranean zone or formation, the hydrostatic pressure exerted on the walls of the well bore can exceed the fracture gradient of the zone or formation and cause fractures to be formed in the zone or formation into which the cement composition is lost. In some instances, lightweight cement compositions (e.g., foamed cements or cements with low density additives such as hollow glass beads) are used to overcome this issue.
However, the preparation of lightweight cement compositions is often difficult, in the case of glass beads, they are buoyant and lightweight and tend to rise out of the slurry. Moreover, their lightweight nature allows the beads to be easily blown around by movement of the air, which changes the final cement slurry composition. Accordingly, in many instances especially at off-shore well-sites, cements with low density additives are used sparingly if at all. Rather, foamed cements, which are several times more expensive than the low-density additive cements, are used. Further, the equipment and materials needed to produce foamed cements occupy a significant amount of space, which is already limited at offshore well sites.